[tex] a.\\P=2x+2\pi r\\\\b.\\2x+2\pi r=P\ \ \ |-2\pi r\\\\2x=P-2\pi r\ \ \ |:2\\\\x=\dfrac{P}{2}-\pi r\\\\c.\\P=660\ ft,\ r=50\ ft\\\\x=\dfrac{660}{2}-50\pi=(330-50\pi)\ ft\approx330-50\cdot3.14=330-157=173\ ft [/tex]
